Method of determining the liquid level in a clothes washing machine



June 18, 1963 c. A. COBB ETAL 3,093,341

METHOD OF DETERMINING THE LIQUID LEVEL IN A CLOTHES WASHING MACHINEOriginal Filed Aug. 22, 1960 3 Sheets-Sheet 1 James T 14411142417715June 18, 1963 c. A. COBB ETAL 3,093,841

METHOD OF DETERMINING THE LIQUID LEVEL IN A CLOTHES WASHING MACHINEOriginal Filed Aug. 22, 1960 3 SheetsSheet 2 ESLZ ,E5l4

[HI EHfUPE (CL/tan, a. (of! James T lr/tllz'ams June 18, 1963 c. A. COBBETAL 3,

METHOD OF DETERMINING THE LIQUID LEVEL IN A CLOTHES WASHING MACHINEOriginal Filed Aug. 22, 1960 3 Sheets-Sheet 3 90 ff g 6 [771/5 27f 0P5(Li/ton d. (01% JameJ 77 Williams United States Patent 3,093,841 METHODOF DETERMINING THE LIQUID LEVEL IN A CLGTHES WASHING MACHINE Clifton A.Cobb and James T. Williams, St. Joseph, Mich assignors to WhirlpoolCorporation, St. Joseph, Mich, a corporation of Delaware Originalapplication Aug. 22, 1960, Ser. No. 51,226, new Patent No. 3,065,618,dated Nov. 27, 1962. Divided and this application Jan. 18, 1962, Ser.No. 167,109 3 Claims. (Cl. 8-153) This invention relates to laundryapparatus and particularly to automatic water level control meanstherefor capable of determining and maintaining the laundryliquid-to-wash load ratio at an optimum value by utilizing a torquesignal generated in the machine by the agitator.

This application is a division of the copending Clifton A. Cobb andJames T. Williams application filed August 22, 1960, under Serial No.51,226, now Patent No. 3,065,618.

Currently, automatic washing machines essentially utilize any one ofthree available methods for controlling the water in the tank or tubthereof. These methods are, first, filling the tub to a maximum level bymeans of a maximum water level control switch; second, selectivelyfilling the tub to any of, for example, three levels by means of a threeposition water level switch, and third, selectively filling the tub toany level between a maximum and minimum by means of an infinite controlwater level switch. The first method is objectionable in that there isno variation possible in the level, regardless of load size. The secondand third methods are objectionable in that they are dependent upon thejudgment of the operator, and if a decision is made which isinappropriate for a given load, the choice can only be modified by afurther decision involving an increase of the amount of water in thetub, which may also be unsuitable.

The present invention eliminates these difiiculties by automaticallyintroducing an amount of water into the tub which is optimum for therequirements of a specific load. This result is achieved by employingthe principle of a torque signal. For example, when a given load issupplied with an insufiicient amount of water, torque from the agitatorwill be transmitted through the load to the basket and the tank. As theagitator oscillates, therefore, the torque transmitted through the loadto the basket and tank produces corresponding movement of the basket andtank which can be sensed and used as a signal. When an addi tionalincrement of water has been added to the tank or tub which is sufficientfor the load, the desired transmission of torque is reduced to asomewhat smaller value. This happens since there is enough water presentin the basket with the load whereby the torque of the oscillatingagitator cannot be transmitted to the basket and tank. This, of course,is logical since it is well known that water will not support shearforces. Thus, although the amount of torque produced by the load when nowater is present is quite substantial, when the load is properlyimmersed the torque is reduced to an insignificant level. Accordingly, atorque signal can be utilized to afford a highly accurate control of theamount of water in the tank regardless of the load size or of the typesof fabric included in the load make-up.

Desirably, the washer of the invention also incorporates a minimum andmaximum water level switch. Pneumatic or electrical means may beutilized for the torque signal pick-up, but a mercury sensor switch hasbeen found highly effective for this purpose, and this switch isutilized in conjunction with the minimum and maximum water level switch.The minimum water level switch assures that a load will not be agitatedwithin the basket when there is an entire absence of water in the tub,and thus serves as a safety device. Similarly, the maximum water3,093,84l Patented June 18, 1963 level switch limits the amount of waterto a predetermined safe level so that extra heavy loads will notintroduce more water in the machine than it can hold.

:Circuit hold relay and time delay relay means are used with the mercurysensor switch so that successive small increments of water areintroduced into the basket until such time as the agitation or torquetransmitted to the tub is below the critical level, thus indicating thatthe optimum amount of water is present for the load.

Accordingly, it is an object of the present invention to provide awashing machine having an automatic Water level control which providesthe correct amount of water for a given load regardless of the types offabric used or of the load size.

Another object of the invention is to provide an automatic washer whichsaves hot water by eliminating filling of the tub beyond the amountnecessary, with consequent savings in water and fuel.

Another object of the invention is to provide a device as indicatedwhich affords a substantial saving in the amount of detergent used,inasmuch as the detergent used 18 proportionate to the Water use.

Yet another object of the invention is to provide a washer which isunusually long-lasting, since the torque transmitted from the agitatorto the basket, and the ensumg stresses and strains are eliminated in theoperation of the machine.

Other objects and advantages of the invention will become apparent asthe description proceeds in accordance with the drawings in which:

On the drawings:

FIGURE 1 is a perspective view of a washing machine with which the waterlevel control of the invention may be advantageously utilized, and whichis broken away to afford a view of the operating parts thereof;

FIGURE 2 is a top plan view in schematic form of a washing machine, suchas shown in FIGURE 1, and liquid level control means therefor;

FIGURE 3 is a vertical elevation view, also in schematic form, of thestructure shown in FIGURE 2;

FIGURE 4 is a top plan view in schematic form of the water level controlmeans of the invention in combination with a different type of washingmachine;

FIGURE 5 is a diagrammatic showing of mercury sensor switch means foruse in controlling the water level in a washing machine; and

FIGURE 6 is a circuit diagram of means cooperating with the sensingmeans shown in FIGURE 5.

As shown on the drawings:

Although the invention is applicable to various types of washersincorporating different types of agitators, the exemplary machinedisclosed herein is of the vertical axis type utilizing an oscillatoryagitator. Referring to the drawings, a washing machine 10 is shown inFIGURE 1, and in schematic form in FIGURES 2 and 3, wherein the waterlevel may be automatically controlled by water level control means 12,as shown in FIGURE 2. As seen more particularly with respect to FIGURE1, the Washing machine 10 may include a cabinet 14 with a lid 16, and aback 18 including a control panel 19 having presettable sequentialcontrol means 20 for operating the machine automatically through aprogrammed schedule of Washing, rinsing and extracting periods. Selectortype switches operated by push buttons 21 condition the circuitryassociated w ith the control means 2B for special operating cycles asdesired by the operator, for example, in selecting water temperature,delicate goods cycles, etc. A foraminous basket 22 is mounted on a spintube 24 for actuation by drive and brake mechanism 26 energized by amotor 28. The basket 22 is mounted in an outer tub or tank 30 andclothes are agitated by an agitator 32 in the basket as also understoodby those skilled in the art.

A water entry hose 34 communicates with a mixing valve 36 and a waterinlet 38 for introducing water into the basket, and an air gap vacuumbreak 40 may be provided. Recirculating hoses 42 and 44- are connectedto a uni-directional drain and recirculating pump 46, drain and sudsreturn hoses 48 and 50 being connected with the pump 46 and with anautomatic two-way valve 52. Hose 50 connects with the drain outlet 51from the tank \01 tub 30.

In the form shown in FIGURES 1 through 3, the tub 30 is mounted by meansof a three-point ball and rod suspension system, a rod 54 being shown inFIGURE 1 as pivotally connected to a base plate 56 for the tub by ballmeans 58 in a socket 60. Other rods 62 and 64- are illustrateddiagrammatically in FIGURES 2 and 3, the upper ends of the rods 56, 62and 64 being pivotally connected to the top of the cabinet 14.

The tub 30 is formed with a rim 66 extending radially inwardly anddownwardly over the basket 22, and in a preferred form of the invention,a snubber 68 is attached to the cabinet 14 and presses down on the rimor tub ring 66 to damp the oscillations produced during operation of themachine as hereinafter described. Where such l3. snubber is utilized,the suspended operating system will tend to rotate about a pivot pointaiforded by the snubber 68 as a result of the torque transmitted fromthe agitator 32 to the suspended system since the snubber represents theonly semi-stationary point of the suspended system. Pneumatic orelectrical sensing means may be positioned on the tub or any locationreceiving the torque described, and in the form shown, the inventionprovides for placing a mercury sensor switch 70, as seen in FIGURES 1,2, 3 and 4, for the level control means 12, at a point which issubstantially the farthest distance away from this stationary pivotingpoint. Thereby, the amplitude of the sensed signal is increased.Location of sensor switch 70 in positions closer to the snubber 68 willresult in reduced torque signals.

It will be understood, however, that the method of automatic water levelcontrol of the invention will be entirely effective even though asnubber is not utilized in the machine, since the suspended system wouldstill oscillate from the suspension rods 54, 62 and 64 because of thetransmission of torque from the agitator through the load to the basketand tank.

Thus in the embodiment of FIGURES 1 through 3, the mercury sensor 70 maybe disposed substantially diametrically opposite thepivot point atfordedby the snubber 68, so that the signal will be maximized, and as seen inFIGURE 5, the means 70 may include a mercury tube 72 which may besecured such asto tub 33 at an adjustable angle so that the mercury 74will contact switch contact means 76 upon oscillation of agitator 32when there is not enough water present in tub 30. Switch contacts 76 areprovided with electrical leads 78 and 80 so as to incorporate switch 76into a control circuit such as shown in FIGURE 6.

Although FIGURE shows :a mercury switch to be used as the torque sensor,it should be understood that other torque sensors such as pneumatic orhydraulic could beused. It is also important to realize that thelocation of these sensors on the laundry machine is not critical as longas they are capable of sensing the torque that is transmitted throughthe clothes load from the agitator when the clothes load is not immersedin the proper amount of water. Once this torque is sensed, the sensorsmust be able to initiate means to add water to the clothes load'untilthe torque becomes somewhat smaller.

As seen in FIGURE 4, the signal actuating means 12a may be mounted on amachine a of the pedestal type, so that the tub 39a is supported on apedestal (not shown) which extends upwardly from the base of themachine. If desired an anti-rotating bar 82 may be pivotally connectedbetween the cabinet and the tub, and as shown, the device 1211 and themercury switch 70 thereof is mounted diametrically opposite the bar 82so that signal forces afiorded by the torque from the oscillation of theagitator 32a will be maximized from the pivot point atlorded by the saidbar.

Referring to FIGURE 6 there is shown a circuit diagram incorporating thesubject water level control. Included in this circuit is a timer motor86 which drives timer motor operated cams 109, 110, 111, 112 and 113 tooperate their corresponding switches 109a, a, 111a, 112a and 113a tooperate a washing machine such as shown in FIGURE 1 through a cycle ofoperation. The positioning of the timer cams is controlled bypresettable sequential control means 20. Other elements controlling theoperating functions of the washing machine through a cycle of operationare the main drive motor 94, the agitation control solenoid 96, waterinlet valve 88 and the spin control solenoid 108.

As shown in FIGURE 6, the switch 76 of mercury sensor 79 is shown asnormally open in the circuit diagram schematically represented, and willclose when the agitator transmits torque through the load to the basketand tank to the extent that the short jerky oscillations of the basketand tank assembly force the mercury 74 in the mercury sensor switch 70to momentarily close this switch 76. The automatic washer is started byadvancing the timer or presettable sequential control means 20* into itsfirst time unit of operation, which closes switch M941, and closing thepush-pull line switch 84 associated with the control means 20. At thistime, the water inlet solenoid 88 associated with mixing valve 36 willbe energized through a minimum water level switch 90 in its emptyposition shown at E, and through a normally closed maximum water levelswitch 92. Thus water will be introduced into the machine through thewater inlet 38 until the minimum water level switch 90 switches from itsempty to its full position shown at F. Thereupon, the timer motor 86 andthe machine motor 94 are energized through the full position of theminimum water level switch independent of cam operated switch 1110a. Theagitation solenoid 96 is also energized at the said full position of theminimum water level switch 90 through its cam operated switch 111a sothat the agitator 32 will start to oscillate, and the washing processwill begin.

If at this time there is sufiicient water in the basket for the loadbeing washed, i.e., so that the load is immersed to a sufficient extentto reduce torque to a desirable minimum, the machine will proceedthrough the rest of the cycle with-out further Water being introducedinto the tub.

However, the usual load will require more water in that with only aminimum amount of water the agitator will transmit torque through theload to the basket and tank or tub, thereby closing the mercury switch76 as described. This closing of the switch 76 of mercury sensor switch'70 will be an impulse only long enough so that both the circuit holdrelay 98 and the time delay relay 1% in parallel therewith will beenergized through the normally closed contacts 102 connected with thetime delay relay 100. When the circuit hold relay 98 is thus energized,the normally open contacts 104 and 106 connected therewith will close,thereby energizing the circuit hold relay 98 and time delay relay 1%through contact 104 to provide a holding circuit.

At the same time, the water inlet solenoid 88 will be energized throughrelay contact 106, the maximum water level switch 92 and cam operatedswitch 112a to introduce a further increment of water into the machine,in accordance with the need therefor indicated by the energization ofthe mercury switch 76.

The time delay relay desirably is constructed to permit water to enterthe machine for a predetermined small interval so that a quite accuratedetermination of the optimum water level in the machine is alforded. For

aooasal example, the time delay relay may be of the dash pot type, sothat, e.g., a period of five seconds may elapse before the normallyclosed contacts 102 open. Opening of these contacts thus de-energizesboth the time delay relay IM and the circuit hold relay 98 to effectdeenergization of the solenoid 88.

If an insuflicient amount of water is added by the increment thusafforded, the torque reaction produced through the load and basket tothe tub will again energize the mercury switch 76 temporarily so thatthe described cycle .is repeated.

As hereinabove stated, the signal aflorded by the switch 76 of mercurysensor switch '70, particularly in its position diametrically oppositethe pivot point afforded by the snubber 68, is highly sensitive, so thatthis procedure may be repeated until the optimum point is quiteaccurately located. The sensitivity of the system can be furthercontrolled by adjusting the angle of the longitudinal axis of themercury sensor switch 7i) with respect to the tub 31). This adjustmentserves to change the torque necessary for the mercury 74 to contactswitch 76 and also allows for adjustments that are necessary betweendifferent production machines or if different agitation speeds are to beused.

In the usual case, small increments of water will be added to the basket22 so that the water will reach an optimum level intermediate theminimum and maximum levels determined by the switches 91] and 92.

However, it will be understood that if an extra heavy load is put intothe machine, torque will continue to be transmitted from the agitator tothe tub and basket and the water will be introduced in successiveincrements until the maximum level is reached. Thereupon, the maximumwater level switch 92 will open, so that the machine may then proceedthrough its normal cycle.

The sensitivity of the system is, in part, controlled by the timeselected between the energization of the time delay relay ltiti and theopening of its normally closed contacts 192. If a five second time delayrelay is utilized, approximately one-quarter to one-half a gallon ofwater, for example, will be added for every energization of the Waterinlet solenoid 88. When it is considered that the maximum Water levelswitch will open at, for example, from 17 to 18 gallons in the machine,it will be seen that the margin of error in determining the optimumWater level will be quite small.

Although a circuit whereby the Water inlet solenoid 88 is in series withthe mercury sensor switch 70 may be utilized within the scope of theinvention, the relatively short impulses afforded by the mercury sensorswitch might be somewhat less satisfactory than the time delay operationdescribed.

Accordingly, there has been provided an automatic Washing machine whichcan be filled to the appropriate level for a specific load without anymanual operations being required, and without the exercise of judgmenton the part of the operator. The machine is highly effective in savinghot water and detergents, so that considerable economy of operation isafforded, and the reduction in wear on the machine by the elimination oftorque and vibration during the agitation cycle assures an unusuallylong life for the machine.

Although we have herein set forth and described our invention withrespect to certain specific principles and details thereof, it will beunderstood by those skilled in the art that these may be varied withoutdeparting from the spirit and scope of the invention as set forth in thehereunto appended claims.

We claim:

1. The method of filling a clothes washing machine having aliquid-receiving, movably-mounted container and an 'oscillatableagitator therein with an optimum quantity of Washing fluid for varyingclothes loads inserted in said container, comprising: adding a minimalquantity of washing fluid to said container, initiating oscillation ofsaid agitator to commence the process of washing the clothes loadinserted in said container, sensing the declining torque transmittedfrom said agitator to said container as washing fluid is added to saidcontainer, and terminating the addition of Washing fluid to saidcontainer when the torque transmitted to said container declines to apredetermined value.

2. The method of filling a clothes washing machine having 'aliquid-receiving, movably-mounted container and an oscillatable agitatortherein with an optimum quantity of washing fluid for varying clothesloads inserted within said container, comprising: initiating the fillingof said container by directing a stream of washing fluid into saidcontainer, initiating oscillation of said agitator subsequent to theinitiation of the filling of said container, monitoring the decliningtorque transmitted from said agitator to said container through theclothes load and Washing fluid carried within said container as saidstream continues to fill said container, and terminating the addition ofWashing fluid to said container when the torque transmitted to saidcontainer declines to a predetermined minimum value.

3. The method of filling a clothes washing machine having aliquid-receiving, mov'ably-mounted container and an agitator movabletherein with an optimum quantity of washing fluid for varying clothesloads inserted within said container, comprising: adding a minimalquantity of washing fluid to said container, initiating movement of saidagitator within said container to commence the washing of the particularclothes load inserted therein, sensing the magnitude of forcestransmitted to said container through said clothes load, and terminatingthe addition of washing fluid to said container when said forces declineto a predetermined minimum value due to the addition of the Washingfluid to said container.

Adams Mar. 1, 1932. Briss et al Feb. 21, 1961

1. THE METHOD OF FILLING A CLOTHES WASHING MACHINE HAVING ALIQUID-RECEIVING, MOVABLY-MOUNTED CONTAINER AND AN OSCILLATABLE AGITATORTHEREIN WITH AN OPTIMUM QUANTITY OF WASHING FLUID FOR VARYING CLOTHESLOADS INSERTED IN SAID CONTAINER, COMPRISING: ADDING A MINIMAL QUANTITYOF WASHING FLUID TO SAID CONTAINER, INITIATING OSCILLATION OF SAIDAGITATOR TO COMMENCE THE PROCESS OF WASHING THE CLOTHES LOAD INSERTED INSAID CONTAINER, SENSING THE DECLINING TORQUE TRANSMITTED FROM SAIDAGITATOR TO SAID CONTAINER AS WASHING FLUID IS ADDED TO SAID CONTAINER,AND TERMINATING THE ADDITION OF WASHING FLUID TO SAID CONTAINER WHEN THETORQUE TRANSMITTED TO SAID CONTAINER DECLINES TO A PREDETERMINED VALUE.